System and method of controlling vehicles to follow a defined trajectory in a complex track network

Abstract

The present invention relates generally to ground transportation systems. According to certain aspects, the present invention includes systems and methods that provide a higher degree of precision and a greater coordination of vehicle movement than is possible in conventional systems. For example, a control system according to the invention is designed to enforce vehicle movement along a route to a position versus time trajectory. The control system includes control equipment on the vehicle that reports its location on the track every 0.5 seconds. The controlling computer in the station receives the report, and knowing where the vehicle should be and how fast it should be traveling at that point in time via a run definition table prepared for the route, calculates a position and velocity error, and then calculates and sends a tractive effort (force) adjustment command to the vehicle that attempts to reduce the position and velocity error.

What is claimed is: 
     
       1. A method of controlling a vehicle in a transportation system, the method being implemented by a computer, the method comprising:
 receiving a table that defines a trajectory for the vehicle, wherein the table comprises a plurality of jerk values, each of the jerk values having a corresponding time and a corresponding jerk duration; 
 computing, using the computer, a current target position for the vehicle based on the jerk values and corresponding times and jerk durations from the table, wherein computing the current target position includes synchronizing a current update interval to one of the corresponding times in the table of jerk values for the vehicle, wherein synchronizing includes:
 determining a relative time difference between the current update interval and an initial time, 
 identifying one or more jerk values in the table having corresponding times closest to the determined relative time difference, and 
 using the identified one or more jerk values to develop the current target position; 
 
 receiving feedback from the vehicle about its actual position; and 
 using the target position and the actual position to develop commands to cause the vehicle to follow the defined trajectory. 
 
     
     
       2. The method according to  claim 1 , wherein the using step includes:
 calculating a position error using the actual position and the target position; 
 estimating a best guess command using the target position; and 
 adjusting the best guess command using the position error. 
 
     
     
       3. The method according to  claim 1 , wherein the commands have values that each correspond to an expected velocity of the vehicle. 
     
     
       4. The method according to  claim 2 , wherein the using step further includes developing feedback terms using the calculated position error, wherein the feedback terms are used to adjust the best guess command. 
     
     
       5. The method according to  claim 4 , wherein the feedback terms are PID terms. 
     
     
       6. The method according to  claim 1 , wherein the steps are all performed in a system that is remote from the vehicle. 
     
     
       7. The method according to  claim 1 , wherein certain of the steps are performed in a system that is remote from the vehicle, and certain other of the steps are performed in the vehicle. 
     
     
       8. A system for controlling a vehicle in a transportation system, comprising:
 a master computer, remote from the vehicle, that creates a table that defines a trajectory for the vehicle, wherein the table comprises a plurality of jerk values, each of the jerk values having a corresponding time and a corresponding jerk duration; 
 a computer remote from the master computer that receives the table and: 
 computes a current target position for the vehicle based on the jerk values and corresponding times and jerk durations from the table, wherein computing the current target position includes synchronizing a current update interval to one of the corresponding times in the table of jerk values for the vehicle, wherein synchronizing includes:
 determining a relative time difference between the current update interval and an initial time, 
 identifying one or more jerk values in the table having corresponding times closest to the determined relative time difference, and 
 using the identified one or more jerk values to develop the current target position; 
 
 receives feedback from the vehicle about its actual position; and 
 uses the target position and the actual position to develop commands to cause the vehicle to follow the defined trajectory. 
 
     
     
       9. The system according to  claim 8 , wherein the remote computer develops commands by:
 calculating a position error using the actual position and the target position; 
 estimating a best guess command using the target position; and 
 adjusting the best guess command using the position error. 
 
     
     
       10. The system according to  claim 8 , wherein the commands have values that each correspond to an expected velocity of the vehicle. 
     
     
       11. The system according to  claim 9 , wherein the remote computer further develops commands by developing feedback terms using the calculated position error, wherein the feedback terms are used to adjust the best guess command. 
     
     
       12. The system according to  claim 11 , wherein the feedback terms are PID terms. 
     
     
       13. The system according to  claim 8 , wherein the remote computer is entirely implemented in a system that is remote from the vehicle. 
     
     
       14. The system according to  claim 8 , wherein certain portions of the remote computer are implemented in a system that is remote from the vehicle, and certain other portions are implemented in the vehicle. 
     
     
       15. The method of  claim 1 , further comprising computing a current target velocity and a current target acceleration based on the jerk values and corresponding times and jerk durations from the table, such that the current target location, the current target velocity and the current target acceleration for a given point in time are all computed from one or more common jerk values from the table. 
     
     
       16. The system of  claim 8 , wherein the remote computer further computes a current target velocity and a current target acceleration based on the jerk values and corresponding times and jerk durations from the table, such that the current target location, the current target velocity and the current target acceleration for a given point in time are all computed from one or more common jerk values from the table.